JPS61275050A - Antiskid control device - Google Patents

Abstract

PURPOSE:To prevent grake fluid pressure from being excessively increased or decreased by correcting the computed wheel speed to be accelerated or decelerated based on both the condition of brake fluid pressure and the rotational inertia of wheels. CONSTITUTION:A change-over control between an inlet valve 14 and an outlet valve 15 is functioned by an antiskid control circuit based on the signal detected by a wheel speed sensor 1 when brake is applied. And change in wheel speed is estimated based on both the condition of brake fluid pressure and the rotational inertia of wheels, and then, the computed wheel speed to be accelerated or decelerated is corrected on the basis of the resultant estimated above. Thus, even if there is a delay in computing the wheel speed to be accelerated or decelerated, the wheel speed to be accelerated or decelerated is corrected to a more realistic value.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention calculates wheel acceleration/deceleration based on an output signal from a wheel speed sensor when braking a vehicle using brake fluid pressure, and calculates wheel acceleration/deceleration based on the output signal from a wheel speed sensor. The present invention relates to an improvement of an anti-skid control device that prevents wheels from locking by controlling the brake fluid pressure based on the above-mentioned brake fluid pressure.

(Prior art) The coefficient of friction μ between the wheels of a vehicle and the road surface is generally approximately 15
%), the maximum μ(WaX) is reached, and at this time the braking efficiency of the vehicle is maximized. Therefore, in normal anti-skid control, when braking a vehicle, the brake fluid pressure is controlled by increasing, decreasing, or maintaining the brake fluid pressure so that the wheel slip rate λ is always around a predetermined slip rate λ0. It is.

As a result, it is possible to shorten the stopping distance during braking, and to ensure steering stability.

By the way, in such an anti-skid control device, in order to maintain the slip ratio λ as close to a predetermined slip ratio λθ as possible under various road surface conditions, wheel acceleration/deceleration is taken into account, and the wheel deceleration is controlled while the braking fluid pressure is being increased. The pressure increase is interrupted when the speed exceeds a predetermined value (when the degree of reduction in wheel speed becomes large enough), and when the wheel acceleration exceeds a predetermined value while the brake fluid pressure is being reduced. It is being considered to interrupt the pressure reduction (when the degree of increase in wheel speed becomes large to a certain extent). In this case, the brake fluid pressure is not controlled to an excessively high or low fluid pressure under any road surface condition, but always changes in a region near the fluid pressure p (lock) at which the wheels are on the verge of locking. This makes it possible to shorten the stopping distance and ensure steering stability.

Conventionally, there is an anti-skid control device that performs switching control of brake fluid pressure in consideration of wheel acceleration/deceleration as described above, as disclosed in Japanese Patent Application Laid-open No. 137160/1983.

(Problem to be solved by the invention) However, in detecting the wheel acceleration/deceleration,
Calculate based on the output signal from the vehicle speed sensor that detects the wheel speed (wheel rotation speed), for example, based on the difference (wheel speed change) between the wheel speed at a predetermined time and the wheel speed at another time. Therefore, the detection of wheel acceleration/deceleration is delayed compared to the detection of wheel speed. In other words, as shown in FIG. 16, for example, when the brake fluid pressure P increases, the wheel speed VW decreases as shown, and even if the actual wheel deceleration αW is as shown by the dashed line, the calculation The wheel deceleration αW is shown as a solid line. Therefore, the actual wheel deceleration αW is the predetermined value b
1, the pressure increase of the brake fluid pressure P must be interrupted as shown by the dotted line at the instant t1 when the calculated wheel deceleration reaches the predetermined value b1, but the interruption of the pressure increase will not start until the instant t2 when the calculated wheel deceleration reaches the predetermined value b1. Therefore, the undesired layer pressure of the brake fluid pressure P continues between instants t1 and t2. As a result, the brake fluid pressure would rise significantly above the above p(+ock), and depending on the situation, there was a possibility that the wheels would lock.

Similarly, during pressure reduction control, the timing of detecting wheel acceleration equal to or higher than a predetermined value is delayed, so that the brake fluid pressure is lower than the above P(lo
ck), resulting in a longer stopping distance for the vehicle.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and its principle will be explained as follows.

Equation of motion of the wheel % formula % (1) ■: Single wheel rotational inertia small: Wheel rotational angular acceleration r: Wheel rotation radius μ: Single wheel coefficient of friction with the road surface W: Wheel weight Tb At the brake torque, the minute time Δ[ The brake torque Tb is ΔTb
If the wheel weight W and friction coefficient μ change by 6℃
Since it can be assumed that there is no change during the period of time, from the above formula, I·Δproduct−ΔTb is obtained (however, the 6th product is the amount of change in the wheel rotational angular acceleration during 61 hours).

Here, since the brake torque change ΔTb is considered to be proportional to the braking fluid pressure change ΔP during that time, (2) ΔR = -β·ΔP (2) β: proportionality constant.

From the above equation, it is found that the change in wheel acceleration/deceleration ΔαW (=rΔ small) can be estimated from the braking fluid pressure state ΔP and the rotational inertia I of the wheel, and if the calculated wheel acceleration/deceleration is corrected from this estimation result, Based on the theory that the above-mentioned problems can be solved, the present invention calculates wheel acceleration/deceleration based on the output signal from the wheel speed sensor when braking the vehicle using brake fluid pressure, and based on the calculated wheel acceleration/deceleration, the above-mentioned problem is solved. In an anti-skid control device that controls brake fluid pressure,
It comprises means for detecting the state of the brake fluid pressure, means for detecting the rotational inertia of the wheels, and correction means for correcting the calculated wheel acceleration/deceleration based on the detection outputs from both of these means. .

(Function) In such a configuration, the correction means estimates the change in wheel acceleration/deceleration from the state of the brake fluid pressure and the rotational inertia of the wheel detected by both of the above means, and corrects the calculated wheel acceleration/deceleration according to the result. Accordingly, the problem regarding the delay in detecting the wheel acceleration/deceleration can be eliminated.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing the basic configuration of an anti-skid control device according to the present invention. That is, basically, this anti-skid control device (anti-skid control circuit 100) controls the wheel 102 output from the wheel speed sensor 1 during braking.
Based on a detection signal with a frequency proportional to the rotation speed of the wheel cylinder 1, the master cylinder 101 of the brake hydraulic system
03 (hereinafter referred to as EV valve 14)
) and an outflow valve provided in the front stage of the reservoir tank 104 and pump 17 in the hydraulic pressure recovery path from the wheel cylinder 103 to the mask cylinder 101 via the reservoir tank 104 and the pump 17 for hydraulic pressure recovery. 15 (hereinafter referred to as AV valve 15). Then, the hydraulic pressure of the wheel cylinder 103, that is, the braking hydraulic pressure, is controlled as shown in the following table by the switching signal of the Ev valve 14 (hereinafter referred to as the EV double signal) and the switching signal of the AV valve 15 (hereinafter referred to as the AV signal). shall be

Table 1 Here, the specific configuration of the anti-skid control circuit 100 will be explained with reference to FIG. In the figure, 2 is a wheel speed detection circuit that calculates the wheel speed Vw based on the output signal from the wheel speed sensor 1, and 3 is an acceleration/deceleration detection circuit that detects the wheel acceleration/deceleration. For example, the third
As shown in the figure, the comparison circuit 60 shapes the AC detection signal from the wheel speed sensor 1 into a pulse signal, and the calculation unit 61 calculates the acceleration and deceleration (negative acceleration) of the wheel based on the pulse period. At the same time, the calculated value is temporarily stored in the memory 62. Then, each time the calculated value in the calculation unit 61 is updated, the calculation unit 61 outputs an update signal Sa, and the memory 62 outputs the calculated wheel acceleration/deceleration αW. In FIG. 2, numeral 4 indicates a pseudo vehicle speed generation circuit that generates a pseudo vehicle speed (hereinafter referred to as pseudo vehicle speed Vi) necessary for detecting the slip ratio λ, and 5 indicates a detection decrement from the acceleration/deceleration detection circuit 3. This is a comparator circuit that outputs an H level signal (hereinafter referred to as b1 signal) when the speed is equal to or higher than a reference deceleration b1, and the pseudo vehicle speed generating circuit 4 generates a signal every time the b1 signal from the comparator circuit 5 is input, for example, at that time. A pseudo vehicle speed Vi that is a speed straight line with a predetermined constant slope from the detected wheel speed value output from the wheel speed detection circuit 2,
Alternatively, a pseudo vehicle speed ■1 is output, which is a speed straight line connecting the wheel speed detected when the bl signal was input last time and the wheel speed detected this time. Reference numeral 6 denotes a target wheel speed generation circuit, which calculates a slip ratio λ0 (see FIG. 15) at which the braking efficiency is near the maximum based on the pseudo vehicle speed Vi from the pseudo vehicle speed generation circuit 4 (see FIG. 15) λo = 1− (
The output is the target wheel speed VIIIO, which is the control target corresponding to
), the calculation of Vwo=V i X O,85 is performed and the calculated value is output.

7 inputs the target wheel speed VWO from the target wheel speed generation circuit 6 and the detected wheel speed VW from the wheel speed detection circuit 2, and when the detected wheel speed VW becomes lower than the target wheel speed Vwo, an H level signal @( A comparator circuit 8 outputs a slip signal (hereinafter referred to as a slip signal), which basically outputs a (level signal @
Similar to the comparison circuit 5, a comparison circuit 9 outputs an H level signal (b
This is a comparison circuit that outputs a + signal). Then, an AND signal (AV
81 signal from the comparator circuit 8 and the b signal from the comparator circuit 9 are input to the AV valve 15 via the driver 13.
1 signal and the output signals from Ando Goo 1 to 10 by the OR gate 11 (EV multiplied signal is sent to the driver 12
The signal is input to the EV valve 14 via the EV valve 14.

16 is a reset circuit that is activated at the rising edge every time the output signal (AV signal) from the AND gate 10 is input, and outputs an H level signal (hereinafter referred to as MR multiplied signal) for a predetermined period of time (for example, about 2 seconds). This is a triggerable timer, and the MR multiplication signal from this retriggerable timer 16 operates the pump 17 for hydraulic pressure recovery.

Reference numeral 18 denotes an acceleration/deceleration correction circuit which is a main part of the present invention, and is used to correct the calculated wheel acceleration/deceleration αW from the acceleration/deceleration detection circuit 3 to the comparison circuit 8.9. For this purpose, in addition to the calculated wheel acceleration/deceleration, the correction circuit 18 uses the above-mentioned three
Input the a signal, the EV multiplied signal, the AV signal, and the MR multiplied signal.

Also, as is clear from the above equation (2), the wheel represented by r・Δω ↓ Also, within the minute time Δ, ΔP= (C) Δt [C is the rate of change in brake fluid pressure within the minute time] need to know what it is. On the other hand, “and β and C
is a constant, but when this is a driving wheel, the rotational inertia I of the wheel includes the transmission and engine, and therefore varies depending on the selected gear position of the transmission. Therefore, a value obtained by multiplying the brake fluid pressure change speed C of the inertia determination t, which will be described below, is also input to the acceleration/deceleration correction circuit 18 as the signal B.

The inertia determination circuit 70 includes a gear position sensor 1 that detects the gear position of the transmission (in this example, neutral, 1st speed to 5th speed), and switches 72 to 77 that are turned on by a power supply voltage E for each gear position. , an adder circuit 78, a constant setter 79, and a divider circuit 80 are provided. The switch 72 has one end directly grounded and the other end grounded via a resistor 81. switch 7
One end of 3 to 77 has a constant voltage of 9Va, 4Va, respectively.
i, sva, 1. OVa, 0.5Va, and the other end is commonly grounded via a resistor 81. Thus, the switches 72-77 control the rotational inertia from the transmission to the engine, which varies depending on the gear position of the transmission. A voltage signal corresponding to a is generated and inputted to the adder circuit 78. The adder circuit 78 is further supplied with a voltage signal vb corresponding to the rotational inertia 1b from the wheels to the transmission, which is constant regardless of the gear position.

The addition circuit 78 adds the two mold pressure signals to obtain the rotational inertia I (=Ia + Ib) of the wheel, and inputs the corresponding signal to the division circuit 80. The division circuit 80 has the above-mentioned (3)
Constant setter 7 that outputs a constant voltage corresponding to -r and β in the formula
By dividing the signal from 9 by the signal r and β from the adder circuit 78, -□ in the above equation (3) is expressed as (5
-□・Signal B corresponding to J-work is input to the acceleration/deceleration correction circuit 18.

A specific example of the configuration of the acceleration/deceleration correction circuit 18 is shown in FIG.

In this figure, 21 is the OR gate 11 in FIG.
A switch 22 is controlled on/off by an AND signal from an AND gate 26 with an inverted signal of the AV signal from the AND gate 10;
Turns on by the NOR signal from the NOR gate 21 of the V signal.
The off-controlled switch 23 is a switch that is on-off controlled by an AND signal from an AND gate 28 of the EV signal and AV signal. In addition, each switch 21.2
2.23 is turned on when the control signal is at H level. Reference numeral 25 denotes an integrating circuit composed of a resistor R, a capacitor C1, and an operational amplifier 25a.The input terminal of this integrating circuit 25 is connected to the ground potential via the switch 21, and to the potential 10B via the switch 22. switch 23
The inverted potential -B by the knot gate 31 is selectively applied to each of the two terminals via the not gate 31. In addition, a bypass switch 24 is connected to both ends of the capacitor C, and this switch 24 is connected to both ends of the capacitor C.
4 is on/off control [(on state when at H level) by the OR signal from the OR gate 30 of the update signal Sa from the acceleration/deceleration detection circuit 3 and the MR multiplied signal inversion signal from the retriggerable timer 16 in FIG. shall be carried out.

29 is the calculated wheel acceleration/deceleration αW from the acceleration/deceleration detection circuit 3
and the output signal from the integrating circuit 25, and the output from the adding circuit 29 is inputted as the corrected wheel acceleration/deceleration [αW] to the comparison circuits 8 and 9 in FIG.

Here, as is clear from the above table, the H level signal from the AND gate 26, the H level signal from the NOR gate 27, and the H level signal from the AND gate 28 are used to maintain, increase, and reduce the brake fluid pressure, respectively. It becomes a detection signal. Also,
As mentioned above, the change ΔP in the brake fluid pressure depends on the minute time Δt
can be considered to be proportional to the change time Δt, ΔP=(C)·Δt(C): Brake fluid pressure change rate within minute time Next, the operation of this device will be explained.

First, to explain the basic operation, when the driver depresses the brake pedal and the braking fluid pressure (hydraulic pressure in the foil cylinder 103) increases, the wheel speed decreases and the wheel deceleration αW (negative acceleration) increases. Here, when the wheel deceleration further increases and reaches a predetermined value b', the b1 signal is output from the comparator circuit 9, and the b1 signal (EV low signal is activated by the EV low signal) and the braking is applied. The hydraulic pressure increase control is interrupted and held at that point.At this time, when the wheel deceleration reaches a predetermined value b1, the pseudo vehicle speed generating circuit 4 generates a predetermined value from the detected wheel speed at that point. A pseudo vehicle speed Vi having an inclination is output, and at the same time, a target wheel speed VWO (=Vi x O, 85) corresponding to the slip ratio λG is sequentially output from the target wheel speed generation circuit 6.Then, the braking as described above is performed. By maintaining the hydraulic pressure at a high hydraulic pressure, the wheel speed further decreases to the above target wheel speed VW.
0, a slip signal is output from the comparison circuit 7, and the AV valve 15 is actuated by the slip signal (AV signal) via the AND gate 10, and the same slip signal (EV low signal) via the OR gate 11 is activated. by EV
The valve 14 is maintained in its operating state, and the brake fluid pressure is reduced. When the brake fluid pressure is reduced in this way, the wheel speed and wheel acceleration are restored, and the wheel acceleration is set to the predetermined value a1.
When the signal 81 is reached, the comparison circuit 8 outputs the signal 81, and the a1 signal (E, V signal) causes the OR gate 11 to continue operating the EV valve 14, while the a1 signal disables the ungate 10. From then on, the AV valve 15 returns to its initial state, and the pressure reduction control of the brake fluid pressure is interrupted and maintained at that point. If the brake fluid pressure is maintained at a relatively low pressure in this way, once the wheel speed exceeds the target wheel speed and increases to a certain extent (at this point the slip signal disappears), it will start decreasing again. At the same time, the wheel acceleration also decreases from the predetermined value 81 or more. Here, if this wheel acceleration falls below the predetermined value a1,
The a1 signal from the comparator circuit 8 falls, and together with the fact that the outputs from the comparator circuits 7 and 9 at that point are at the L level, the EV low signal AV signal goes to the L level, and the braking fluid pressure increases again. The pressure will be increased. Then, the wheel speed and wheel acceleration further decrease, and thereafter, the same control of the brake fluid pressure as described above is repeated one after another.

That is, the switching control of the brake fluid pressure during braking is performed according to a control mode determined based on the wheel acceleration/deceleration αW and the slip ratio λ (actually Vw/Vi) as shown in FIG. .

Next, in the overall operation as described above, the more detailed operation including the operation of the acceleration/deceleration correction circuit 18 will be explained with reference to the timing chart shown in FIG. After starting braking, the detected wheel speed VW becomes the target wheel speed VWO (-Vt x 0
．． Until the moment t1 reaches 85 ), there is no AV signal output, that is, no MR multiplied signal is output, so the switch 24 is turned on and the output of the integrating circuit 25 is held at "0", and the adding circuit 29 is The acceleration/deceleration correction circuit 1
The output [αW] from 8 has the same value as the calculated wheel acceleration/deceleration αW output from the acceleration/deceleration detection circuit 3 together with the update signal Sa. When the AV signal rises with the rise of the slip signal from the comparator circuit 7 at instant t1, the MR multiplied signal is output accordingly, so the switch 24 is turned off, while the pressure is reduced (EV=)(', AV= H)
The switch 23 is turned on by the output signal from the AND gate 28 serving as a detection signal. Then, the calculated wheel acceleration output at instant t1 is added, and the acceleration/deceleration correction circuit 18
The output [αW] increases with time with a slope corresponding to (B/CR) from the calculated wheel acceleration/deceleration αW at the instant t1. Then, at the instant [2], the acceleration/deceleration detection circuit 3 outputs a new calculated wheel acceleration/deceleration αW along with an update signal Sa.
is output, this update signal Sa causes switch 2 to
4 is momentarily turned on, the integral circuit 25 is cleared at that moment, and the output [αW] from the acceleration/deceleration correction circuit 18 momentarily becomes the calculated wheel acceleration/deceleration αW at the instant t2. After that, since the switch 23 is kept in the on state (during pressure reduction control), the output of the integration circuit 25 becomes the integrated value of the potential -B, and the output [αW] from the acceleration/deceleration correction circuit 18 becomes this new value again. From the calculated wheel acceleration/deceleration αW, the above (B/C
It further increases with time with a slope corresponding to R).

When the output [αW] of the acceleration/deceleration correction circuit 18 rises and reaches the predetermined value a1 at the instant t3, the AV signal falls as the a1 signal from the comparator circuit 8 rises.
The brake fluid pressure at that point is maintained. At this time (instant t3
), the output of the AND gate 28, which is the pressure reduction detection signal, falls and the switch 23 turns off, and the hold (
EV=)-1, AV=1) Since the output of the AND gate 26, which is a detection signal, becomes H level and the switch 21 is turned on, the integrating circuit 25 will integrate the ground potential from now on. , the output of the integrating circuit 25 stops increasing, and the output [αW] from the acceleration/deceleration correction circuit 18 maintains the output value at instant t3.

Then, at instant t4, an update signal S is sent from the acceleration/deceleration detection circuit 3.
When a new calculated wheel acceleration/deceleration αW is output together with a,
Similarly to the above, the integration circuit 25 is cleared and the output [αW] from the acceleration/deceleration correction circuit 18 becomes the calculated wheel acceleration/deceleration αW. From then on, the integration circuit 25 integrates the ground potential, so the acceleration/deceleration correction circuit Output from 18 [αW]
is the same value as the calculated wheel acceleration/deceleration αW output from the acceleration/deceleration detection circuit 3 together with the update signal Sa.

Here, at instant t5, the output from the acceleration/deceleration correction circuit 18 [
αW) (calculated output from acceleration/deceleration detection circuit 3, acceleration value) is less than predetermined value a1, then b from comparison circuit 9 has already been detected.
Since the 1 signal is falling, the 8 from the comparator circuit 8
When the EV 1 signal falls, the EV multiplier signal falls, and from that point (instantaneous
), the output of the AND gate 26, which serves as the holding detection signal, falls and the switch 21 turns off, and at the same time the pressure increases (
Since the output of the NOR gate 27, which serves as a detection signal (EV=L, AV=L), becomes H level and the switch 22 is turned on, the integration circuit 25 integrates the potential element B, and its output The value (integral value) is. Then, the output from the acceleration/deceleration correction circuit 18 [α
W] is the sum of the above integral value to the calculated wheel deceleration αW at instant t5, and the output (αW) changes over time from the calculated wheel deceleration αW at instant t5 with a slope corresponding to (-B/CR). In this way, when the output (αW) from the acceleration/deceleration correction circuit 18 decreases and reaches the predetermined value b1 (deceleration) at instant t6, the output (αW) from the comparison circuit 5 decreases.
1 signal causes the pseudo vehicle speed generation circuit 4 to generate a new pseudo vehicle speed Vi, and at the same time, the bl signal from the comparator circuit 9 rises, the EV multiplier signal rises, and the braking fluid pressure at that point is maintained. At this time (instantaneous [6]), the output of the NOR gate 21, which becomes the pressure increase detection signal, rises and the switch 2
2 turns off, the output of the AND gate 26, which becomes the holding detection signal, becomes H level again, and the switch 21
is in the on state, from now on, the integrating circuit 25 will integrate the ground potential as described above, and this integrating circuit 2
5 stops increasing, and the output [αW] from the acceleration/deceleration correction circuit 18 maintains the output value at instant t6. Then, at instant t7, when a new calculated wheel acceleration/deceleration αW is output from the acceleration/deceleration detection circuit 3 together with the update signal Sa, the integration circuit 25 is cleared in the same way as above, and the output from the acceleration/deceleration correction circuit 18 [αW ] becomes the calculated wheel acceleration/deceleration αW, and while the brake fluid pressure P is maintained and controlled, the integrating circuit 25 integrates the ground potential, so that the output [αW] from the acceleration/deceleration correction circuit 18 becomes the calculated wheel acceleration/deceleration αW. This value is the same as the deceleration αW.

Furthermore, after that, that is, the target wheel speed Vw is the same as the wheel speed Vw relative to the pseudo vehicle speed Vi that occurred at the instant t6.

(= Vi

As described above, according to this embodiment, while the reduced pressure state of the brake fluid pressure is being detected, the calculated wheel acceleration/deceleration value output at a predetermined point in time is proportional to ΔVw=(B)・Δ[ A value corresponding to the integral value of the potential -B corresponding to the constant (B) is added to correct the wheel acceleration/deceleration so that it increases with time from the calculated value, while an increase in the braking fluid pressure is detected. During this period, a value corresponding to the integral value of the potential element B corresponding to the proportionality constant (B) is added to the calculated wheel acceleration/deceleration value output at a predetermined point during that time, and the wheel acceleration/deceleration is determined from the calculated value. We fixed it so that it decreases over time, so
By appropriately determining the time constant OR of the integrating circuit 25, the wheel acceleration/deceleration, which is a control parameter while detecting the decrease and increase in brake fluid pressure, approaches the actual value. The moment when the wheel acceleration/deceleration αW exceeds the predetermined value a1, which is a condition for interrupting decompression [instant before [4]
At an instant t6 before the instant t7 when the corrected wheel acceleration/deceleration [αW] reaches a predetermined value (mat) and the calculated wheel acceleration/deceleration exceeds a predetermined value b1 (deceleration) which is a condition for interrupting pressure increase. The corrected wheel acceleration/deceleration (αW) reaches the predetermined value b1.As a result, it is possible to prevent the braking fluid pressure from increasing or decreasing excessively.Moreover, the above potential B is determined by the speed change as described above. Since the rotational inertia of the wheels, which differs depending on the gear position of the machine, is taken into consideration, the above-mentioned effect of bringing the wheel acceleration/deceleration close to the actual value can be reliably achieved at any gear position.

Next, other embodiments shown in FIGS. 8 to 11 will be described.

Now, the wheel cylinder 103 in FIG.
The hydraulic pressure increase characteristics are as shown in FIG. 7 (the pressure reduction characteristics are reversed). In addition, when braking on a high μ road surface, the hydraulic pressure at which the wheels are on the verge of locking is relatively high.
(lock), and when braking on a low μ road surface, the hydraulic pressure is relatively low P.

(1ock). Therefore, in the anti-skid control, the braking fluid pressure P is Ph (lock) on a high μ road surface.
On a low μ road surface, the braking fluid pressure P will increase or decrease within the region E2 near P, (lock), but the rate of change in fluid pressure at that time (ΔP/Δ() differs depending on whether it is a high-μ road surface or a low-μ road surface (because the characteristics shown in Figure 7 are not linear).In other words, the preferable proportionality constant (C) at ΔP= (C)・Δt is based on the road surface at that time. It changes depending on μ, that is, the 1b11 dynamic hydraulic pressure P.

In view of the above, in the present embodiment, the brake fluid pressure P corresponding to the road surface μ at that time is indirectly known, and the correction constant for the calculated wheel acceleration/deceleration is changed accordingly.

As shown in FIG. 8, its basic configuration is approximately the same as that of the embodiment shown in FIG. Specifically, the configuration is shown in FIG. 9, and the inertia discrimination circuit 70 uses the fact that the slope A information of the pseudo vehicle speed Vi from the pseudo vehicle speed generation circuit 4 changes depending on the road surface μ to calculate the slope A information. Based on acceleration/deceleration correction circuit 1
The correction constant 8' of the calculated wheel acceleration/deceleration towards 88' is changed. The specific configuration of the acceleration/deceleration correction circuit 18a is shown in FIG.

Here, to explain the configuration of the pseudo vehicle speed generation circuit 4, the ninth
In the figure, 40a is M from the retriggerable timer 16.
Inverted signal via R-fold signal inverter G2 and comparison circuit 5
A sample hold circuit 40b extracts and holds the detected wheel speed VW from the wheel speed detection circuit 2 in synchronization with the AND signal from the AND gate G1 with the b1 signal from the b1 signal. 41 is a timer counter that increments at a predetermined period; 400 is a sample and hold circuit that extracts and holds the numerical value of the timer counter 41 in synchronization with the output signal from the AND gate G1; This is a sample hold circuit that extracts and holds the numerical value of the timer counter 41 in synchronization with the b1 signal. 42 is a subtraction circuit that reduces the sampling value vb of the sample and hold circuit 40b from the sampling wheel speed value ■0 of the sample and hold circuit 40a, and 43 is a subtraction circuit that calculates the numbering value Tb of the number hold circuit 40d from the sampling value To of the sample and hold circuit 40c. 44 is a subtraction circuit that performs subtraction, and numeral 44 is a subtraction circuit for subtracting the subtracted value (Vo −Vb) from the subtraction circuit 42.
This is a division circuit that divides by the subtracted value (To - Tb) from 3.

Further, 45 is a slope generation circuit that generates a slope signal corresponding to a predetermined wheel speed slope signal, for example, 0.4G, and 46 is a slope signal from the slope generation circuit 45 and a calculation output (Vo - Vb)/from the division circuit 44. (To -Tb), and 47 is a switch for switching the sampling (+[Tb) held in the sample and hold circuit 40d.
(n) a subtraction circuit that subtracts the output value from the timer counter 41 from the subtraction circuit 48; 49 is a subtraction circuit that subtracts the calculation output from the multiplication circuit 48 from the detected wheel speed values sequentially sampled by the sample and hold circuit 40b. 50 is an RS flip-flop (hereinafter simply referred to as FF
According to the output Q of this FF 50, the changeover switch 46 is set to the slope generating circuit 45 side when the output Q is a torque level, and to the multiplier circuit 4 when the output Q is a torque level.
It is assumed that the switch can be switched to each of the four sides.

Further, 51 is a retriggerable timer that outputs a torque signal for a predetermined period (for example, 2 SeC) from the rise of the b1 signal from the comparison circuit 5, and 52 is a subtraction circuit 49 for subtracting the pseudo vehicle speed v1 output to the target wheel speed generation circuit 6. This switch 52 switches to the output from the retriggerable timer 51 or the detected wheel speed Vw from the wheel speed detection circuit 2, and this switch 52 switches to the subtraction circuit 49 side when the output Q from the retriggerable timer 51 is at torque level. do.

Next, the pseudo vehicle speed generating circuit 4 as described above during braking
The operation will be explained with reference to the timing chart shown in FIG. When braking is started and the wheel deceleration reaches the predetermined deceleration b1 for the first time at an instant to, b1 is output from the comparison circuit 5.
The sample and hold circuit 40 synchronizes with the rising edge of the signal.
The detected wheel speed from the wheel speed detection circuit 2 is sampled at a and 40b as the value Vb (0) = Vo, and the count value from the timer counter 41 is sampled at the sample and hold circuit 4001 and 40d in synchronization with the rise of the b1 signal. Tb(0)=To is sampled. Also,
At this point, FF50 is not set because it is the AV double signal torque in the control device, and this FF50
The output Q holds the torque and the changeover switch 46 is on the slope generation circuit 45 side. Then, as time elapses until the wheel deceleration reaches the predetermined value b1 again, the subtraction circuit 47 outputs a count value Tc corresponding to the elapsed time Tc = T-Tb (0) T: The output value of the timer counter 41 is sequentially At the same time, based on this count value TC and the slope value AO (0, 4G>) from the slope generation circuit 45, a value Ao xTc corresponding to the speed reduction value is sequentially output from the multiplication circuit 48. , Vb (0) - AOXTC as the pseudo vehicle speed Vi is output from the subtraction circuit 49, and after the first rise of the b1 signal, the subtraction circuit 49 is
The above-mentioned pseudo 2. Vb (0)-Ao xTc as similar vehicle speed vi
is supplied to the target wheel speed generation circuit 6.

That is, in the first skid cycle from when the wheel deceleration reaches the predetermined value b1 at the instant to until the wheel deceleration reaches the same value bl again, the slope AO changes from the detected wheel speed value ■(0) at the instant to. A pseudo vehicle speed Vi having a characteristic that decreases with .

Next, when the wheel deceleration reaches the predetermined value 11b again at instant t1, the detected wheel speed value vb(1) at that time is changed to the corresponding bl
The signal is newly sampled by the sample hold circuit 40b in synchronization with the signal, and the timer counter 4 at the same time
The count value Tb(1) from 1 is newly sampled by the sample and hold circuit 40d in synchronization with the same bl signal. Also, at this time, the MR from the retriggerable timer 16
The double signal is at H level, the AND gate G1 is disabled, and the sample and hold circuit 40a further holds the values Vb (0) and Tb (0) in the circuit 400, and the FF 50 is set. The changeover switch 46 is switched to the division circuit 44 side and held there (hereinafter,
This state continues). Here, the subtraction circuit 42 calculates the difference ΔVb (1) between the detected wheel speed value vb (0) at the instant to and the detected wheel speed value Vb (1) at the instant t1. ΔVb (1) - Vb (0) -Vb (1) is output from the subtraction circuit 43 at the instant t.

The difference value ΔTb (1) ΔTb (1) - Tb (0) - Tb (1) between the count (lflTb (0)) at instant t1 and the count value Tb (1) at instant t1 is output, and the difference value ΔVb (1), ΔTl) (1)
Based on this, the division circuit 44 calculates ΔVb(1)/ΔTb1), and converts this calculated value A1 from Vb (O) to V
It is output as slope information leading to b(1). Then, as time elapses until the wheel deceleration further reaches the predetermined value b1, the subtraction circuit 47 sequentially outputs the count value Tc Tc -T-Tb (1) corresponding to the elapsed time, and this count value A value A I .Furthermore, from the subtraction circuit 49, Vb
(1) -A+XTC is output as a pseudo vehicle speed.

That is, in the second skid cycle after the wheel deceleration reaches the predetermined value b1 at the instant t1 until the wheel deceleration reaches the same value bl again, the slope A1 changes from the detected wheel speed value Vb(1) at the instant [+]. A pseudo vehicle speed Vi having a characteristic that decreases with .

Similarly, each time the wheel deceleration reaches the predetermined value b1 in each skid cycle, the difference between the detected wheel speed value at that time and the first detected wheel speed value vb(0) under the same conditions and the time interval ( Then, until the wheel deceleration reaches a predetermined value b1, a pseudo vehicle speed vi that decreases with the above-mentioned slope from the detected wheel speed value at that time is output. .

By the way, as mentioned above, the detected wheel speed Vb(0) when the wheel deceleration reaches the predetermined value 1iib+ at the start of braking is the same as the detected wheel speed Vb(0) under the same conditions in each skid cycle.
n), that is, the slope A of the pseudo vehicle speed Vi that occurs in each skid cycle indicates the decreasing tendency of the vehicle speed at the time of occurrence. Therefore, when this slope A is large, it means that the road surface μ is relatively large, and the braking hydraulic pressure at that time is also controlled in a relatively high hydraulic pressure area.If the slope A is small, then
This is a case where the road surface μ is relatively small, and the braking fluid pressure at that time is also controlled in a relatively low fluid pressure region.

Therefore, as shown in FIG.
The structure is similar to that described above in the figure, but the multiplication circuit 82
is added, and the above-mentioned pseudo vehicle speed slope information A and the constant -r·β from the constant setter 79 are inputted thereto. Multiplication circuit 82
is inputted to the information brightness correction circuit 18a of these input information,
The acceleration/deceleration correction constant can be appropriately changed by the pseudo vehicle speed slope information A, that is, by the road surface μ as is clear from the above.

Therefore, as shown in FIG. 11, the acceleration/deceleration correction circuit 18a has the same basic configuration as the acceleration/deceleration correction circuit 18 shown in FIG. - The above signal B' is applied to the switch 22 which is controlled off, and the inverted output -8' of the signal B' by the NOT gate 31 is applied to the switch 23 which is controlled on and off by the pressure reduction detection signal (output of the AND gate 28). input.

The correction operation of the acceleration/deceleration correction circuit 18a is substantially the same as that in the embodiment shown in the timing chart of FIG. 6, but when the brake fluid pressure is reduced, the calculated wheel acceleration/deceleration value is output at a predetermined point in time A value corresponding to the integral value of the signal (potential) is added to -, and the wheel acceleration/deceleration is corrected so that it increases over time with a slope of (B'/CR) from the calculated value. When increasing the pressure, the value corresponding to the calculated wheel output at a predetermined point in time is added, and the wheel acceleration/deceleration is corrected so that it decreases over time with a slope of (-8'/CR) from the calculated value. It becomes like this.

As described above, according to the present embodiment, the slope A of the pseudo vehicle speed Vi becomes large in the control in the region where the brake fluid pressure P is high, that is, in the region where the rate of change ΔP/Δt is large, so that the acceleration/deceleration of the wheel is controlled. While the correction constant (B'/CR) increases,
Control in a region where the brake fluid pressure P is low, that is, its rate of change ΔP/
In a region where Δt is small, the slope A becomes small, so the correction constant (B'/CR) becomes small. Therefore, the corrected acceleration/deceleration [αW] can be brought closer to the actual value than in the above embodiment.

Figures 12 to 14 show still other embodiments of the present invention. In this example, the 12th
As is clear from the figure, the acceleration/deceleration detection circuit 3 detects the wheel acceleration/deceleration by performing differential processing on the detected wheel speed from the wheel speed detection circuit 2. The update signal Sa is not output like this. Accordingly, the acceleration/deceleration correction circuit 18b in this example does not perform the synchronous operation based on the update signal Sa as described above, but
The configuration is as shown in the figure. This circuit 18b is basically the same as that shown in FIG.
A retriggerable timer 33 is provided which is activated at the rising edge of the holding detection signal from the NOR gate 27, the pressure increase detection signal from the NOR gate 27, or the pressure reduction detection signal from the AND gate 28, and outputs an H level signal for a predetermined period of time.
The switch 24 which prohibits the correction operation by the integrating circuit 25 is controlled by the output Q+ from the retriggerable timer 33 via the retriggerable timer 2.

In the acceleration/deceleration correction circuit 18b, as shown in FIG. 14, while the MR multiplied signal is output and the output of the retriggerable timer 33 is at H level, the
．． Between t3 and j4+j5 and t6, the same corrections to the calculated wheel acceleration/deceleration as shown in FIG. 6 are made.

In addition, in the above three embodiments, the change in wheel acceleration/deceleration ΔαW (
QCΔF) is proportional to the brake fluid pressure change ΔP ■・Δ product = -
Focusing on the fact that β・ΔP, the braking fluid pressure change ΔP is calculated based on ΔP=(C)・Δt (in the second embodiment, (C) is the pseudo vehicle speed
This is an attempt to estimate the change in wheel acceleration/deceleration ΔαW1, that is, the amount of correction of the wheel acceleration/deceleration αW, based on the degree of the brake fluid pressure change ΔP (variable according to the slope A of 1). , wheel cylinder 10
3 (see FIG. 1) may be provided with a hydraulic pressure sensor for direct detection.

(Effects of the Invention) Thus, the anti-skid control device of the present invention has the following effects as described above.
Since the calculated wheel acceleration/deceleration αW is corrected according to the state of the brake fluid pressure and the rotational inertia of the wheels, even if there is a delay in the calculation of the wheel acceleration/deceleration, the wheel acceleration/deceleration [αW], which is a control parameter, is The brake fluid pressure is corrected to a value close to reality, and therefore, it is possible to prevent the brake fluid pressure from increasing or decreasing excessively. In particular, since the above correction takes into account the rotational inertia of the wheels, even in the case of drive wheels whose rotational inertia differs depending on the gear position of the transmission, the corrected acceleration/deceleration [αW] can be realized at all gear positions. can be very close to the value of , and anti-skid control can be performed accurately.

[Brief explanation of drawings]

Fig. 1 is an overall system diagram showing one embodiment of the anti-skid control device of the present invention, Fig. 2 is an electronic circuit diagram showing an example of the anti-skid control circuit in the device of the present invention, and Fig. 3 is acceleration/deceleration detection in the same example. A block diagram showing a specific example of the circuit, FIG. 4 is an electronic circuit diagram showing a specific example of the acceleration/deceleration correction circuit in the same example, FIG. 7 is an operation timing chart of the embodiment shown in FIGS. 2 to 4, FIG. 7 is a diagram showing changes in hydraulic pressure over time showing changes in hydraulic pressure in a general wheel cylinder, and FIG. 8 is an operation timing chart of the embodiment shown in FIGS. An electronic circuit diagram of an anti-skid control circuit showing an example; FIG. 9 is an electronic circuit diagram of a pseudo vehicle speed generating circuit in the same example; FIG. 10 is an operation timing chart of the pseudo vehicle speed generating circuit; FIG. 12 is an electronic circuit diagram of an anti-skid control circuit showing still another example of the present invention; FIG. 13 is an electronic circuit diagram of an acceleration/deceleration correction circuit in the same example; FIG. 14 is an operation timing chart of the acceleration/deceleration correction circuit, FIG. 15 is a diagram showing the relationship between the coefficient of friction between the wheels and the road surface and the slip rate, and FIG. 16 is the wheel speed during braking by a conventional anti-skid control device. It is a time chart showing changes in brake fluid pressure and wheel acceleration/deceleration. 1...Wheel speed sensor 2...Wheel speed detection circuit 3.
... Acceleration/deceleration detection circuit 4... Pseudo vehicle speed generation circuit 5, 7. 8. 9... Comparison circuit 6... Target wheel speed generation circuit 12, 13... Driver 14... Inflow valve (EV
Valve) 15... Outflow valve (AV valve) 16... Retriggerable timer 11... Pump 18, 18a, 18b... Acceleration/deceleration correction circuit 21
, 22.23.24...Switch 25...Integrator circuit 2B, 27.28...Gate (braking fluid pressure state detection means) 29...Addition circuit 31...Knot gate 33...R Triggerable timer 408 to 40d...Sample hold circuit 41...
Timer counter 42.43.47.49... Subtraction circuit 44... Division circuit 45... Pseudo vehicle speed slope generation circuit 46, 52... Changeover switch 48... Multiplication circuit 50... Flip 70 knob 51... Retriggerable timer 61... Wheel acceleration/deceleration calculation unit 62... Memory 70... Inertia discrimination circuit (wheel rotation synergia detection means) 71... Gear position sensor 72-77...・Switch 78...Addition circuit 79...Constant setter 80
...Divider circuit 81...Resistor 82...Multiplication circuit 100...Anti-skid control circuit 101...Brake master cylinder 102...Wheel 103...Wheel cylinder 104...
・・Reservoir tank

Claims (1)

[Claims] 1. When braking a vehicle using brake fluid pressure, wheel acceleration/deceleration is calculated based on an output signal from a wheel speed sensor, and the brake fluid pressure is controlled based on the calculated wheel acceleration/deceleration. In the anti-skid control device, the above-mentioned means for detecting the state of the braking fluid pressure, the means for detecting the rotational inertia of the wheels, and the correction for correcting the calculated wheel acceleration/deceleration based on the detected outputs from both of these means are provided. An anti-skid control device comprising means.